I sealed my stored 1979 Vespa in a cheap car bubble bag and found a puddle inside after 3 weeks
I put my project Vespa in one of those $60 zip-up storage bags in my garage back in early April and figured that was plenty of protection. When I unzipped it 3 weeks later, there was a puddle of water pooling on the floor mat and beads of condensation all over the frame, so I pulled the bag off and went back to a plain cotton cover. Was it the temp swings in my garage, or do those bags just trap damp air no matter what you do?